Developers laud the potential of Cassandra. "We're looking for scalability," says software engineer Elder Crisostomo of user management service vendor Stormpath. "We're also looking for speed and something that's easily expandable." The company is currently exploring Cassandra in hopes of using it to manage terabytes of data and replace a MySQL database. "As data grows, as it gets bigger and bigger, it gets harder to maintain. I guess Cassandra makes it a lot easier."

Supermarket chain Safeway also is considering Cassandra to help manage customer loyalty programs. "Obviously, we are looking at use cases where we have to scale horizontally. We have large amounts of personalized data for each customer that we are maintaining," says Subroto Chakrabarty, who manages the mobile applications program at Safeway.

Tracking users, Hadoop linkageAt Adconion Media Group, the digital distribution platform vendor is using Cassandra to track users' viewing habits on the Web. "A lot of browsers are getting rid of third-party cookies, and we are using it to attach fingerprints to people so that we can serve ads that are appropriate to a person's interests," says Frank Wierzbicki, Adconion senior software engineer. "It's allowing you to take a lot of reads and a lot of writes very rapidly and store this data."

Additionally, Cassandra can be linked with the Apache Hadoop distributed computing system for data analysis. Cassandra can run with Hadoop or an analytical tool, as the workload is automatically distributed across the cluster, Chakrabarty says.

Cassandra keeps changingWhile Cassandra is heralded for its capabilities, developer Ben Boule, senior software engineer at security services company Rapid7, cites rapidly changing APIs and features as a challenge. "[Cassandra is] exciting, but it's also frustrating, it is changing so fast," he says. "It seems like it's easy to force yourself into a corner where you have to rewrite your work."

Still, Cassandra so far is meeting the company's needs as far as scaling, and it will be used for an as-yet-undisclosed product at Rapid7: "We haven't really had any problems with it crashing or anything like that."

Possible PostgreSQL replacementTelecommunications company Flowroute may move to a NoSQL solution such as Cassandra or Riak in place of PostgreSQL. "We have a pretty write-intensive workload," says Trip Volpe, software engineer at Flowroute. "We're getting kind of peak performance from PostgreSQL right now, so we're just looking at our options."

Flowroute needs a database to store records and needs more capacity for a write-heavy workload. "We're looking at ways we can develop a solution and build out and scale horizontally," Volpe says.